Carbon plate

High-quality carbon structural steel is a steel with excellent mechanical properties, and its carbon content usually does not exceed 0.8%. The characteristic of this steel is that compared with ordinary carbon structural steel, it contains less sulfur, phosphorus and non-metallic inclusions, which makes it better in mechanical properties.

According to the national standard GB/T699-1999, high-quality carbon structural steel is mainly composed of carbon (C) element, while in order to achieve the effect of deoxidation, it also contains a certain amount of silicon (Si) (usually not more than 0.40%) and manganese (Mn) (usually not more than 0.80%, but in some cases can be as high as 1.20%). In addition to these main elements, such steels do not contain other alloying elements, unless they are present as residual elements. In the production process, the content of sulfur (S) and phosphorus (P) is strictly controlled, usually kept below 0.035%. If the sulfur and phosphorus content can be controlled below 0.030%, the steel is classified as high quality steel and added to its grade "A" to distinguish it, such as 20A. When the phosphorus content is controlled below 0.025% and the sulfur content is controlled below 0.020%, this steel is called extra high quality steel, and an "E" is added after its grade to make a distinction. In addition, for other residual alloying elements brought in by raw materials, such as chromium (Cr), nickel (Ni), copper (Cu), etc., their content is also strictly controlled, respectively, no more than Cr≤0.25%, Ni≤0.30%, Cu≤0.25%. Some specific grades of manganese (Mn) content can reach 1.40%, this type of steel is called manganese steel.

The mechanical properties of high quality carbon structural steel can be improved by adjusting the carbon content. According to the different carbon content, this type of steel can be further divided into:

Mild steel: carbon content is usually less than 0.25%, such as No. 10 steel, No. 20 steel, etc.

Medium carbon steel: the carbon content is generally between 0.25% and 0.60%, such as 35 steel, 45 steel, etc.

High carbon steel: the carbon content is usually greater than 0.60%. This type of steel is not normally used to make steel pipes.

It is important to note that there are no hard and fast boundaries between these categories.

The output of high-quality carbon structural steel is large and widely used, and it is often processed into round, square, flat and other profiles, plates and seamless steel pipes. They are mainly used to manufacture parts for various general structures and mechanical structures, as well as building structures and pipes for transporting fluids. Depending on the specific use requirements, sometimes these steels need to be heat treated (such as normalizing or tempering) to meet specific performance requirements.